Vertical Structure and Diabatic Processes of the MJO

Vertical Structure and Diabatic Processes of the MJO: A Global Model Evaluation Project

A Joint Research Activity by the WCRP-WWRP/THORPEX MJO Task Force & Year of Tropical Convection (YOTC) and the GEWEX Atmosphere System Study (GASS)

Synopsis: The objective of this project is to characterize, compare and evaluate the heating, moistening and momentum mixing processes associated with the MJO that are produced by our global weather and climate models, with a particular focus on their vertical structure. The goal is to improve our understanding of the role that convection, cloud, radiative and dynamic processes play in the development and evolution of the MJO in order to achieve better fidelity of the MJO in our global prediction models. The experimental framework takes advantage of the known links between biases seen in short-range forecasts and long-term climate simulations. Making use of the ECMWF YOTC analysis and profiling products from contemporary satellites (e.g. TRMM, CloudSat, Calipso, AIRS), along with a set of systematic and complementary model experiments, we will characterize, compare and evaluate the vertical processes associated with the MJO produced by global models. Two types of simulations will be carried out:

Twenty-year climate simulations that provide a characterization of the models’ intrinsic capabilities at representing MJO variability. Model simulations from both ocean-coupled global models as well as those that use specified SSTs are solicited. Output will include information on vertical structure/processes at six-hourly resolution so that adequate information is available for investigating multi-scale interactions.

A series of daily initialized hindcasts for two MJO events within the YOTC period, specifically the two successive MJO events during boreal winter 2009-10 (i.e. YOTC events E and F). A principal focus of this component of the experiment is on providing highly detailed and comprehensive (e.g. every time step) model output over a select near-equatorial Indian Ocean / western Pacific Ocean domain for the initial two days of the hindcasts. This will provide the information needed to scrutinize and analyze the detailed evolution of the model MJO as it progresses from a state near the observed one to the model’s intrinsic variability. This hindcast component will provide the framework from which analogous cases can be examined from the DYNAMO/CINDY field program that is taking place in boreal winter 2011-12.

Differing from (2) only in the level of detailed diagnosis, this component will analyze the performance of the models MJO as a function of forecast lead time from 1 to 20 days. Hindcast components 2 and 3 will provide the framework from which analogous cases can be examined from the DYNAMO/CINDY field program that is taking place in boreal winter 2011-12.

In addition to the overall goal for the project stated above, it is expected that the detailed analysis of physical tendencies of heat, moisture and momentum from the model experiments will be used to define one or more follow-on projects involving process models, as well as to possibly inform needs for future field experiments and observing systems.